/*
 * Copyright 2010 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package de.google.android.apps.iosched.io;

import static de.google.android.apps.iosched.util.ParserUtils.AtomTags.ENTRY;
import static org.xmlpull.v1.XmlPullParser.END_DOCUMENT;
import static org.xmlpull.v1.XmlPullParser.START_TAG;

import de.google.android.apps.iosched.provider.ScheduleContract;
import de.google.android.apps.iosched.provider.ScheduleContract.Sessions;
import de.google.android.apps.iosched.provider.ScheduleContract.Speakers;
import de.google.android.apps.iosched.provider.ScheduleContract.Vendors;
import de.google.android.apps.iosched.util.Lists;
import de.google.android.apps.iosched.util.Maps;
import de.google.android.apps.iosched.util.ParserUtils;
import de.google.android.apps.iosched.util.WorksheetEntry;

import org.apache.http.client.methods.HttpGet;
import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;

import android.content.ContentProviderOperation;
import android.content.ContentResolver;
import android.net.Uri;
import android.util.Log;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;

public class RemoteWorksheetsHandler extends XmlHandler
{
	private static final String TAG = "WorksheetsHandler";

	private RemoteExecutor mExecutor;

	public RemoteWorksheetsHandler(RemoteExecutor executor)
	{
		super(ScheduleContract.CONTENT_AUTHORITY);
		mExecutor = executor;
	}

	@Override
	public ArrayList<ContentProviderOperation> parse(XmlPullParser parser, ContentResolver resolver)
			throws XmlPullParserException, IOException
	{
		final HashMap<String, WorksheetEntry> sheets = Maps.newHashMap();

		// walk response, collecting all known spreadsheets
		int type;
		
		while ((type = parser.next()) != END_DOCUMENT)
		{
			if (type == START_TAG && ENTRY.equals(parser.getName()))
			{
				final WorksheetEntry entry = WorksheetEntry.fromParser(parser);
				
				Log.d(TAG, "found worksheet " + entry.toString());
				sheets.put(entry.getTitle(), entry);
			}
		}

		// consider updating each spreadsheet based on update timestamp
		considerUpdate(sheets, Worksheets.SESSIONS, Sessions.CONTENT_URI, resolver);
		considerUpdate(sheets, Worksheets.SPEAKERS, Speakers.CONTENT_URI, resolver);
		considerUpdate(sheets, Worksheets.VENDORS, Vendors.CONTENT_URI, resolver);

		return Lists.newArrayList();
	}

	private void considerUpdate(HashMap<String, WorksheetEntry> sheets, String sheetName, Uri targetDir,
			ContentResolver resolver) throws HandlerException
	{
		final WorksheetEntry entry = sheets.get(sheetName);
		
		if (entry == null)
		{
			// Silently ignore missing spreadsheets to allow sync to continue.
			Log.w(TAG, "Missing '" + sheetName + "' worksheet data");
			return;
		}

		final long localUpdated = ParserUtils.queryDirUpdated(targetDir, resolver);
		final long serverUpdated = entry.getUpdated();
		
		Log.d(TAG, "considerUpdate() for " + entry.getTitle() + " found localUpdated=" + localUpdated + ", server="
				+ serverUpdated);
		
		if (localUpdated >= serverUpdated)
			return;

		final HttpGet request = new HttpGet(entry.getListFeed());
		final XmlHandler handler = createRemoteHandler(entry);
		
		mExecutor.execute(request, handler);
	}

	private XmlHandler createRemoteHandler(WorksheetEntry entry)
	{
		final String title = entry.getTitle();
		
		if (Worksheets.SESSIONS.equals(title))
		{
			return new RemoteSessionsHandler();
		}
		else if (Worksheets.SPEAKERS.equals(title))
		{
			return new RemoteSpeakersHandler();
		}
		else if (Worksheets.VENDORS.equals(title))
		{
			return new RemoteVendorsHandler();
		}
		else
		{
			throw new IllegalArgumentException("Unknown worksheet type");
		}
	}

	interface Worksheets
	{
		String SESSIONS = "sessions";
		String SPEAKERS = "speakers";
		String VENDORS = "sandbox";
	}
}
